(NaturalNews) According to the National Institutes of Health (NIH) about 7.5 million Americans suffer from the chronic, autoimmune skin disease called psoriasis that causes irritated, flaky and thick patches of red skin; some forms of psoriasis are also associated with joint pain. Most medical treatment for the often painful and quality-of-life robbing disease center around controlling symptoms with medications like cortisone. But now research just published in the August issue of the Archives of Dermatology indicates there's a non-drug way to clear and maybe cure the disease naturally -- exposure to vitamin D boosting UV-B light.

Comprising the "tanning rays" from the sun that are blocked by sunscreen and long feared for supposedly causing wrinkles and "age spots", UV-B light, it turns out, actually promotes health by increasing levels of vitamin D. Now a team of scientists from St. Vincent's University Hospital in Dublin, Ireland, have found that treatment with narrow-band UV-B rays greatly increases serum levels of vitamin D in the wintertime. And they've shown how adequate exposure to UV-B light therapy can clear psoriasis. In fact, the new finding is powerful evidence that a lack of the "sunshine" vitamin is involved in the development and worsening of this skin condition.

The researchers studied 30 consecutive patients with psoriasis who were treated with narrow-band UV-B light three times per week between October 2008 and February 2009. The research subjects' psoriasis cleared and their serum vitamin D levels (which were measured before the study, after four weeks of treatment and after the treatment was finished) were compared with those of 30 control patients who also had psoriasis but did not have any UV-B therapy. The researchers also assessed the severity of the patients' psoriasis symptoms and their skin disease-related quality of life before and after treatment.

The results showed that levels of serum 25-hydroxyvitamin D, which is considered the most accurate measurement of vitamin D levels in the body, had increased significantly among individuals receiving UV-B therapy -- rising from about 23 nanograms per milliliter to 59 nanograms per milliliter at the end of treatment. However, there was no change in the control group.

"At the end of the study, all patients in the treatment group were vitamin D sufficient, but 75 percent of the control group had vitamin D insufficiency," the authors wrote in their paper. What's more, the control group's skin condition didn't improve at all. And in the group treated with UV-B light exposure, their psoriasis severity scores decreased dramatically -- from 7.1 at the beginning of the study to only 0.5 after light therapy.